Film production method and film-element production method

Abstract

A method for producing a lead ferroelectric film having high relative dielectric constant and low dielectric loss by a hydrothermal process is disclosed. The method includes the step of hydrothermally forming a ferroelectric layer on a substrate, followed by the step of hydrothermally treating the resulting film in an aqueous solution having a pH of about 5 to 7.

1. A film production method comprising:
 subjecting a hydrothermally formed film to hydrothermally processing in an aqueous solution having a pH of about 5 to 7.  
 
     
     
       2. A method according to  claim 1 , wherein the hydrothermally formed film comprises PZT. 
     
     
       3. A method according to  claim 1 , further comprising hydrothermally forming the film. 
     
     
       4. A method according to  claim 3 , wherein hydrothermally forming the film comprises forming a hydrothermal seed on a substrate and then subjecting the seeded substrate to hydrothermal film formation. 
     
     
       5. A method according to  claim 4 , further comprising the step of forming an electrode on the surface of the film. 
     
     
       6. A method according to  claim 1 , further comprising the step of forming an electrode on the surface of the film. 
     
     
       7. A method according to  claim 6  wherein the hydrothermal treatment is conducted at a temperature of 250° C. or less. 
     
     
       8. A method according to  claim 7  wherein the hydrothermal treatment is conducted at a temperature of 220° C. or less. 
     
     
       9. A film production method comprising:
 forming a ferroelectric seed film comprising at least one of the metals to be contained in a ferroelectric film on a substrate; immersing the substrate in an aqueous solution comprising the metal elements of the ferroelectric film to hydrothermally form a ferroelectric film; and  
 hydrothermally processing the resulting ferroelectric film in an aqueous solution having a pH of about 5 to 7.  
 
     
     
       10. A method according to  claim 9 , wherein the substrate comprises a metal of the ferroelectric film formed. 
     
     
       11. A method according to  claim 10 , wherein
 a substrate comprising titanium is immersed in an aqueous solution containing lead and zirconium and heated to form PbZrO 3  seed crystals on the substrate; and  
 hydrothermally treating the resulting substrate in an aqueous solution containing lead, zirconium and titanium to allow the PbZrO 3  seed crystals to grow and form a film comprising lead zirconate titanate; and  
 hydrothermally processing the resulting film in an aqueous solution having a pH of about 5 to 7.  
 
     
     
       12. A method according to  claim 11  wherein the hydrothermal processing is conducted at a temperature of 250° C. or less. 
     
     
       13. A method according to  claim 12  wherein the hydrothermal processing is conducted at a temperature of 220° C. or less. 
     
     
       14. A method according to  claim 13 , further comprising the step of forming an electrode on the surface of the film. 
     
     
       15. A method according to  claim 12 , further comprising the step of forming an electrode on the surface of the film. 
     
     
       16. A method according to  claim 11 , further comprising the step of forming an electrode on the surface of the film. 
     
     
       17. A method according to  claim 14 , wherein the electrode is formed on the surface of the film after the hydrothermal processing. 
     
     
       18. A method according to  claim 5 , wherein the electrode is formed on the surface of the film after the hydrothermal processing.